End of Days
by Kimberley Jackson
Summary: An AU Crossover with The Walking Dead. Sam/Jack - Stranded in a world destroyed by a zombie apocalypse, SG-1 struggles to fight the deadly outbreak of a virus so they can get back home. While fighting everything in the world around them, Sam and Jack grow closer and have to deal with an inevitable question: do Air Force regulations still apply in a world without rules?


_A/N: Even though this is a crossover, due to the difference in location none of TWD show characters are going to make an appearance. Colorado Springs and the Atlanta/Washington region are just too far from each other to pull that off. :P_

 **End of Days (A Stargate SG-1 / The Walking Dead Crossover)**

Ten days since their return through the Stargate. Ten days since they'd stepped into a completely screwed up version of Earth with no way back. And for ten days everybody had kept looking at her for answers she simply didn't have.

Sam Carter wiped the back of her dirty hand over her face, undoubtedly spreading the dirt and blood around. Her other hand clasped the knife at her side.

Wasn't it amazing how fast humans adapted to extreme situations?

Maybe she just benefitted from her training as a soldier. Still, she was nearing the point of exhaustion. There was no way back—not unless they found a power source for the Stargate. But chances for that looked grim. The batteries in the cars they'd come across so far had all been depleted or were missing.

In front of her, O'Neill halted, his hand shooting up into the air. Her body complied instantly, even before her brain had fully processed the command.

She listened into the silence of the forest. And then she heard it. It came from somewhere ahead of them.

Faint growling. Groaning. The unbearably juicy sound of flesh being torn from bones. She closed her eyes. Not again.

Slowly, she backed off. Avoidance was better than engagement. Those damn things showed up too unexpectedly, and what looked like three or four could turn into a crowd of twenty or more within moments.

Quietly, she turned. Between the trees… She squinted. Movement!

 _Shit._ There was at least one following them. They had to be coming from the nearby road.

Maybe their steps had been too loud after all. Or the creatures were roaming the forest, as usual, and had stumbled across them by accident.

"Sir." Barely a whisper, but she felt his movement behind her. Then his warm breath washed across her face.

"Yeah. I see 'em. That way." He took a left turn through a line of bushes, away from the street and the approaching undead.

She followed him. The branches rustled as he rushed past them, but so far that didn't seem to attract much attention. Every now and then, one of the creatures turned its dead head to them. Stared through empty eyes and moved on.

Maybe it was their uniforms. As much as she wished for a change of clothes, the camouflage did have its advantages.

Ahead, O'Neill stopped and crouched down. She followed his lead. More creatures. Heart pounding, she looked behind her. They had circled them. Shooting was out of the question. That would only draw more, and they didn't have unlimited ammunition.

The underwood still seemed to shield them. But for how long?

Her face grew hot, every muscle in her arms tensing. If even one of those things took an interest in them, it'd be over. Only two days ago, they'd seen a few of them tear a human apart and eat her guts out while she screamed and fought.

She squeezed her eyes shut, trying to drive the image away. Time limped past at a snail's pace, always accompanied by the growls and groans of something worse than death.

 _Daniel._

 _Teal'c._

Her eyes stung. It had been six days since they'd been separated. Maybe they'd both been turned into one of those monsters. What the hell had happened to Earth? This couldn't be their universe.

They had only been gone for a couple of hours before they'd returned through the gate. No way things had gone South this fast. Maybe the Stargate had malfunctioned and brought them to another universe. Or into the future?

All her assumptions were mere speculation without the means to test them. As long as she didn't have a power source, she couldn't use any of the devices in her lab. Without power, they also couldn't leave Earth through the Stargate to contact one of their allies for help.

Upon their return, the Cheyenne mountain base had been deserted. A thick layer of dust covered everything. As though the base had been abandoned. But that wasn't possible in two hours.

"Carter." A hiss. Then a firm grip around her arm.

She opened her eyes. O'Neill's face was right in front of hers. "Let's move. It's now or never. There's more on the other side. You take care of the ones behind us, I take care of the front."

"Yes, Sir." She focused and turned, keeping her back to his.

It was impossible for one person to shield all sides, and in the past, this approach had worked best. Always having each other's back and staying as close to the other as possible.

Breathy growling drifted from somewhere nearby. She whipped around towards it. A moment later, a creature stumbled out from between two trees, its rotting arms stretched out. Guts hung out of his stomach and brushed against its legs with every limp. Dead eyes fixed on her, it opened its mouth. Teeth chattered as the creature tried to bite, still two meters away from her. Once. Twice.

The sound twisted her insides. She fought a shudder and pulled out her knife. How she hated this part.

She plunged forward, aimed, and slammed the knife down into the creature's head. It bucked and sank to the ground. A few cold drops hit her face when she yanked the knife out of its skull.

O'Neill's hand grazed her arm, and without looking back they hurried on through the trees. And more trees. Trees stretching out forever. Like a maze and they were no more than rats running from a horde of starved cats. At last, pavement glistened through the foliage.

Taking a deep breath, Sam stumbled onto a deserted street. Immediately, she turned left. Then right. No creatures. She fastened the knife at her belt and pulled a tissue out of her mission pack. Disgusting. Getting the cold, dead blood all over her was the worst part. And it never stopped.

She rubbed her face frantically until O'Neill grabbed her wrist and took the tissue from her.

"Missed a spot." He rubbed at her hairline and her temple before he gave the tissue back to her. "All gone."

"Thank you, Sir."

"Let's keep moving. That sign over there says we're two miles from Palmer Lake."

"Yes, Sir." She threw the tissue away. Like anyone would care anymore. "We should also stock up food there. We're good until tomorrow, but we'll run into problems if we don't—"

"One thing at a time, Carter. At the moment, I'm more concerned about finding shelter. It'll be gettin' dark soon, and we both need rest."

Good point. She let out a slow breath and lifted her head to the blue sky. White clouds drifted by. How odd that the sky and the stars still looked the same when everything else had changed.

"I hope Daniel and Teal'c are okay." He hated that topic, but who cared. She'd go crazy if they didn't talk about it. Besides, he had to worry about them, too.

"Teal'c's a much better warrior than us, and he still has his staff weapon. That means unlimited ammunition." He kicked a few pebbles with his boot and turned, walking backwards while scanning the area behind them. His voice took on a gentler tone. "They'll be fine. Just like us."

"Fine?" She closed her eyes. Nothing about this was fine. They were _not_ fine.

"They know the plan. They'll be there."

"What if they aren't, Sir?"

He raised his brows at her.

"Well, Sir, what if they don't show up? How long are we going to wait? Will we proceed as planned and leave them behind without—"

"Carter." He grabbed her shoulders. "Can we focus on making it to your house first? Let's not dwell on worst case scenarios. If that happens—and I stress _if_ —we'll figure something out. We always do. And we've been in worse situations."

She cocked her head. "Name one."

He grew thoughtful. Opened his mouth. Closed it again. Finally, he sighed. "Okay, maybe we haven't. But that doesn't mean anything. You'll get us outta here. As soon as we set you up with some power, we'll dial the gate and go to our alpha site. There, you can figure out what went wrong, and we'll reverse it."

If only things were as easy as he said. She forced a smile. "Right."

"Before you know it, we'll back at the real Stargate command. With Hammond and Walter waving us hello through the window of the control room."

She widened her smile at the image, and this time she didn't have to force it. "Yes, Sir."

A distant growl pulled her back into reality. O'Neill's face grew serious. "Let's keep moving before those damn things catch up with us."

* * *

The sun had almost set when the first houses of Palmer Lake stretched out in the distance. Head pounding, Jack glanced around. Having to search the houses in the dark would be a pain in the ass.

They'd settle for the first one and take care of searching for supplies in the rest tomorrow. They both needed to sleep before they took on more of these undead things. Even though Carter didn't complain, she looked like she was on the verge of breaking down. So was he.

If they wanted to make the trip into Colorado Springs to reach her house, they needed to rest. On their first attempt to enter the city from the road leading up to Cheyenne mountain, they'd run into a huge crowd of undead and gotten separated from Daniel and Teal'c. He'd make sure they didn't make that mistake again.

They slowed when they approached the first house. No light glowed in the windows, and no sound drifted from within. He glanced at Carter. "Heads up."

She straightened, hand on her knife. He fisted his hand and pounded on the door three times. Then another three times. If anything drew these damn things out, it was sound.

"Sir."

He turned his head. A creature stumbled out between two houses on the other side of the street. Better not make any more noise. Who knew how many zombies roamed this town.

Quietly, he tried the door. Locked. Damn it. What now? Breaking the lock would also effectively disable their shelter.

Carter touched his shoulder and leaned in. "He saw us, Sir. I'm gonna take care of him before he gets too close and draws the attention of others."

"Okay. But only him. If you see more, get outta there."

"Yes, Sir." She hurried towards the growling shadow limping across the street.

Jack took a step back and looked up at the house's front. There was a half-open window. Shouldn't be too hard to reach.

Behind him, the growling stopped and silence swallowed everything. Only a few seconds later, Carter was back at his side, panting softly. "No sign of any more, Sir."

"Good. At least for the moment." He shook the beam supporting the awning. Not very sturdy, but maybe it'd be strong enough to hold his weight. "Stay here, and keep your head down."

"Sir." She grabbed his arm and her gaze met his. Even in the darkness he saw the concern on her face. "Be careful."

He gave her a smirk. "You betcha." After handing his backpack over to her, he stepped aside and grabbed the metal trellis fastened to the house wall. Just two, maybe three steps up and he could reach the awning. From there, it should be a piece of cake.

He put his foot on the first row and tested it. So far so good. His other foot found hold on the second row. The grid shook and swayed. Then there was a crack as one of the screws came loose somewhere. _Uh oh._

No way would this hold until he reached the awning, and if it crashed down, that'd make an awful lot of noise. He jumped down and returned to the front door. "Change of plan. Let's go around to the back and see if we can find a ladder."

"Yes, Sir." Relief flashed across her face as she handed his gear back to him.

They rounded the corner of the house and climbed over the high metal fence. This was a good sign. If they had trouble getting inside, surely none of the creatures had made it.

Hand at the hilt of his knife, he approached the corner and sneaked a glance into the backyard. Too many dark corners to be sure. He reached for the flashlight in his mission pack and looked at Carter. She gave him a quiet nod.

Jack took a long, deep breath before he shone the beam of the light into the garden. First one corner, then the next. Thick bushes covered the fences and didn't allow for a glance outside. No creatures.

"All right. Let's try the back door."

"Sir, there's a shed over there."

"We can check it out in the morning. I don't wanna take any risks now." Keeping the light on the path ahead, he walked to the small staircase leading up to the back entrance. He closed his eyes when his fingers wrapped around the cold doorknob. _Please let it be open._

He turned the knob. Stuck. Damn. He rattled it.

Something pounded against it from the inside and loud growling drifted through the door. He jumped back and almost fell down the stairs. "Shit."

Carter stopped next to him and they looked at each other for a moment, listening to the growling. "It doesn't sound like more than one, Sir. We could take it."

"Assuming there aren't more inside."

She dropped her arms and looked around. Utter exhaustion flashed across her face. "We don't know if there are any holes in the fence, Sir. So staying out here isn't an option."

She had a point. But neither was moving on. He closed his eyes. "All right. Let's take that thing on and hope for the best."

"Sir?" She raised her brows at him.

"The more time we waste, the higher the chance we're gonna make a mistake. So let's deal with this."

"Yes, Sir."

He set his backpack down and searched through it. A few seconds later, he pulled out the dirty plastic bottle they'd found a few days ago. He took a sip of the stream water and handed it to her. "Drink up. I need the bottle."

She finished the water in a few sips and handed the bottle back to him. He went through the rest of his gear until he found the duct tape. Then he wrapped it around the bottle until all of the plastic was covered. After a quick check of his gun, he placed it in Carter's hand. "Hold that for me."

"Sir, what are you doing?"

"I'm gonna have to shoot the lock. Hopefully this lil' trick will keep the sound down. Won't last for more than a coupla shots though."

He used more duct tape to securely fasten the makeshift silencer to the mouth of his gun. "Get your knife out and keep it ready. As soon as I shoot the lock, that thing will come out. I'll shoot it, but if there's more we're gonna have to use the knives."

"Got it, Sir."

"Ready?"

She gave him a firm nod. He took a few steps back, aimed the gun and fired. A dull thump sounded from inside the bottle, and at the same time metal lock clacked at the door. Slowly, the door opened.

A gaunt creature stumbled outside, fell down the stairs and landed on its face. The neck gave a nasty crack. He flinched. _So that's that then._

Jack lowered the gun. The head still wriggled, and muffled growling reached his ears.

"For cryin' out loud," he muttered and pulled his knife out. A well-aimed stab and silence swallowed them up again. He turned to Carter and took his gear back. Then they entered the dark house.

Once inside, she pulled the door shut behind them. Jack switched on his flashlight. "Hello?"

His voice echoed almost unnaturally between the deserted walls.

"Anyone home?"

Nothing. No growl, no scuffling or anything that indicated a dangerous presence.

Carter approached from behind. "I'll check upstairs, Sir."

He gave her a nod and sneaked through the corridor towards the front door. Should they really be so lucky to have found a house they could use? Something about this was too good to be true.

He flooded the living room with light, checking every corner before he moved to the next. After he'd checked the last room, he hurried back into the living room and pulled the couches in front of the doors. Just to be safe.

In the kitchen, he tried the faucet. If he remembered correctly, Palmer Lake was supplied by a water reservoir in the mountains, which should provide water pressure even without electricity. So maybe…

It splattered, and a slow stream of clear water ran down into the sink. Score. His mood lifted. Maybe there'd be enough for them to take a quick shower and wash some of their clothes.

He hurried to the stairs. He'd almost reached the top when Carter came out of a room, relief on her face. "We're good, Sir. Nobody's here."

"And we got running water."

"Really?" Her beaming smile made his heart jump. Ah, how he'd missed that. Hadn't seen a lot of those in the past week.

"Yeah. Not sure for how long though. So why don't we fill our bottles, take quick showers and wash our clothes?"

"Any food, Sir?"

"Not in the kitchen. There's a basement, but I'd rather look at that in broad daylight." He entered one of the rooms. A bedroom, from the looks of it. A large bed took up most of it.

"I wonder what happened to whoever lived here." Carter strolled inside.

"I wanna bet the creature downstairs was one of them."

"Yeah, but the photos on the walls show a family." She dropped her backpack and glanced around.

"Maybe the one downstairs was someone seeking shelter." He sat own on the bed. Damn, it would be nice to sleep in a real bed. His back was killing him.

"Maybe we'll find some clothes we could wear." Carter strolled over to the wall closet. "Just until ours are dried. We'll put them back."

That was so her. He fell back on the mattress and allowed himself to relax. "I don't think the previous owners are gonna return, Carter. They wouldn't mind us taking a coupla things."

"It still feels like we're looting." She reached for the handle.

The instant she pulled the closet open the hair at the back of his neck stood up. The smell of rotten flesh wafted over. He jerked up but it was too late. Her scream echoed through the house as she hit ground.

* * *

Teeth chattered. Hands clawed at her. That was all she noticed when the pain in her back faded. And then she felt her own hands pushing against the heavy, cold body, keeping it at bay. It wasn't over yet.

She gritted out a scream and shoved the creature off her. Panting, she glanced down. Tiny fingers clawed at her boot, trying to draw her closer. Her blood ran cold.

 _A child. Oh God. The second creature's a child._ Tears blurred her vision.

The cracking of bones made her turn her head. Cold drops hit her cheek. O'Neill crouched next to her, his knife embedded in the adult creature's head. After he'd yanked it out of the creature's skull, he jerked around towards the closet.

She tried to grab his arm. "No, wait. That's—"

"Carter, she's not human anymore." _Crack. Splatter._

An icy fist grabbed her heart. The rest of the family. The mother and their little daughter… They'd died in the closet. The colonel was right. Even if it still looked like a child, it was a monster now, and he was probably doing them a favor by killing them.

Breath hitching, she closed her eyes. This wasn't real. None of it. What kind of hell had they gated into when they returned? None of this made any sense.

She jerked her eyes open when warm hands grabbed her arms. Her shoulders. Brushed the hair away from her checks and neck. "You all right?"

"Y-yes, Sir."

Was she? That attack had come so fast she'd barely felt anything except the pain from hitting the floor. She turned her arm and inspected it. Then the other. No rips or tears in her uniform. Her vest shielded her chest and back.

"S-she must've been too weak to get through my uniform. Sorry, Sir." Despite her shaking legs, she stood up. "I didn't check the closet, because I didn't think there'd be…I…" A child. She stared at the tiny arm peeking out from under a pile of clothes, now lying lifeless.

"That was close." He grabbed her and spun her to face him. His gaze met hers for a split second before he pulled her hard against him, his hand tangling in her hair. "For God's sake."

Her chest shook on a sob as she clutched his jacket. He was right. If this creature hadn't been weakened, she'd be done.

She held his gaze as he cupped her cheek. "Don't scare me like that again, Carter."

"Sorry, Sir."

"You're our only hope at fixing this. Without you, we won't get home."

When his warm lips pressed against her forehead, she froze. "Sir."

He gentled his voice. "Without you, I don't _wanna_ get home. So for cryin' out loud, don't open any damn closets without having your knife ready."

She clutched the fabric of his jacket, not daring to look at him. His words were out of line. Hugging like this was. Him holding her like this. And yet, she didn't want to withdraw. It wasn't like Air Force regulations covered this mess they'd gated into.

"I can't sleep in this room with the bodies on the floor," she said when she finally found the courage to speak. He loosened his grip on her and took a step back. The sudden cold made her shiver. "There's another room with a bed couch, Sir."

She turned to the closet. No way was she touching any of those clothes, knowing those creatures had lived in there. Her gaze stopped once more at the tiny hand. So young. She'd barely started her life.

A low rumbling behind her drew her attention. O'Neill had opened a drawer in the dresser standing at the other side of the bed. He searched through the contents. "There's lots of female underwear and some shirts in here. See if any of it fits and take what you need. We'll move to the other room. I'll bury the bodies in the morning."

"Yes, Sir."

"Is there a tub in the bathroom?"

"Yeah. A shower, too."

"Here. Pick something. Then go and fill the tub with water so we can soak our clothes. If there's any water left we'll take a shower afterwards." He dropped a pile of clothes into her arms and gently pushed her to the door. "I'll go through the rest of this stuff."

She sneaked a last glance at the bodies and left the room.

* * *

The door gave a low squeak. Sam opened her eyes and stared at O'Neill's dark silhouette. The scent of shower soap wafted off him. She lay back against the pillow and stared at the ceiling. Bizarre. The bedsheets smelled like laundry detergent. As though everything were as it used to be.

"There's nothing else in the house. I checked every closet and door." He closed the door and pulled a chair up to it to secure the handle.

"They probably locked themselves in here thinking they were safe."

"Yeah." Groaning, he sat down on the bed. "Why weren't they?"

"Sir?" She turned to him.

"Didn't you say people have to be bitten to turn into one of these things?" He lay down next to her and covered himself with the second blanket.

"That was an assumption, Sir. Besides, he may well have been bitten. Maybe he turned and infected the entire family." He had a point though. The creature that had stumbled out of the house didn't look like it had been feasted on. More like he'd starved. Then again, it'd been dark and they'd barely taken a second look at the one in the backyard.

"You really think that?" He turned to her and held her gaze.

She flinched. "I'm not sure, Sir. At the moment, I wanna believe it, because the alternative is that we're dealing with some kind of airborne infection. In that case, we wouldn't be able to return home, even if we found a way."

"Because we'd take the infection with us and risk repeating the same thing in our universe." He let out a slow breath. "That really sucks."

"Sir, I was thinking…"

"Get out." His eyes gleamed. "Do you ever stop?"

A smiled tugged at her lips. It was good to hear some of his wry humor return. "Even if it was an infection, it doesn't mean we can't do anything. If we get the Stargate to work, we'll contact the Tok'ra for help. Maybe the Asgard if I can get sufficient power."

"Assuming they exist. If this is an alternate universe—"

"Sir, the Air Force _did_ have the Stargate in Cheyenne Mountain even in this universe. There's even a good chance whatever organism caused this was brought to Earth through the Stargate."

He groaned. "Evil Goa'uld attack?"

"Maybe. Or an off-world alien parasite of some sort that broke contamination. My point is, we don't know enough to jump to conclusions. Maybe there's a simple solution to all this. Maybe it's even reversible."

"You tryin' to give me a pep talk, Carter?"

"I'm trying to look on the bright side, Sir. For now, we're safe."

His face softened. "Yes, we are. Why don't we use the time we have and get a good night's sleep? Tomorrow we'll get moving. If we don't run into any major trouble, we might be able to reach your house."

She squirmed under her blanket, trying to get warm. "Is it safe if we both sleep?"

"The doors are barricaded, and the windows downstairs are all boarded-up. If anything or anyone tries to get in, they're gonna make a lot of noise. It'll wake us up."

That sounded good. Soothing even. Still, what if one of those things crept up on them? She shivered, though she wasn't sure it was from cold.

"C'mere." He pulled her close and wrapped parts of his blanket around her. "You're exhausted. No wonder with no more than three hours a night the past ten days."

Her breath hitched when his fresh scent filled her nostrils. So pleasant, and nothing like the smell of rotting flesh and decay that had constantly accompanied them during the past week.

She inched closer and buried her faced against his warm neck. When his grip around her tightened, she brushed her nose along his skin. "Is this okay, Sir?"

He threaded his fingers through her hair. "Yeah." His voice came out a bit throaty.

When his warm hand slipped under her blanket, touching her naked arms and shoulders, she closed her eyes. It wasn't okay. Not even close. She wrapped her arms around his naked chest, pressing herself closer. "You're warm."

"You smell good." His mouth brushed her temple.

 _Uh oh._ "We're gonna get in trouble with the regs. Sir."

He let out a low chuckle. "Not concerned about that at the moment."

She lifted her head and brushed his chin with her nose. If only she could share his careless attitude. But after the Za'tarc test a few months ago, they'd promised to keep the emotions between them in that room.

He swallowed visibly and shifted. "If this is another universe, and worse, if we can't get back, do our rules still apply?"

"Interesting thought, Sir." But even if they ignored the regs now, they'd have to deal with them when they got back home. _If_ they ever got back. And what if they didn't?

An odd excitement stirred in her. She lifted her head and studied his dimly lit face. It was probably a bad idea to even think about this. _And what if I die tomorrow?_

His intense gaze seemed to go to the deepest part of her. "What?"

Mouth dry, she shook her head and buried her face against his shoulder. "Nothing. Good night, Sir."

His grip on her tightened. "Night."

 **~ The End**

 _I'm planning on writing a sequel for this. You will most likely find it on my website first, so click on my profile where you'll find a link. You can also sign up for story updates on my website. :)_


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